The record-setting insect that wasn't

September 5, 2000

It's not always easy to measure how fast a bird or any creature is going. For animals on the run, a scientist may use a stopwatch to time how fast they go between two points. Then the scientist measures the distance between those two points to determine the animal's speed. Birds' flying speeds have been clocked with stopwatches, measured from airplanes, tracked by radar, and tested in wind tunnels. Some of these methods are fairly accurate. But sometimes researchers come up with very different results.

Insects are harder to track because they are so small. They don't always fly in straight lines, either.

In 1927, Charles Townsend took photographs of the botfly in flight. He used the blurred images of the flying insect and the shutter speed of the camera to calculate the botfly's speed. His results, published in a respected scientific journal, declared that the insect could fly 820 miles per hour - a little faster than the speed of sound!

Scientists took his claim seriously for years. But in 1938, Nobel Prize-winner Irving Langmuir challenged Townsend's findings. His own studies showed that the air pressure on an insect at that speed would be so great that it would be squashed in flight. (He was right; the botfly goes only a small fraction of that speed.)

Today, scientists gather more accurate measurements by using sound recordings as the insect passes between two points. High-speed filming is another popular way to gauge speed. Using these methods, the fastest insect known today goes about 60 m.p.h.

Some scientists report clocking insects at 90 m.p.h., but these are unpublished results. Until results are published, people tend not to take them seriously. And even so, as in Charles Townsend's case, even published results may not be right.